import time
from prometheus_client import Counter, Histogram

HTTP_REQUESTS_TOTAL = Counter(
    "http_requests_total",
    "Total HTTP requests",
    ["endpoint", "method", "status"],
)

HTTP_REQUEST_DURATION_SECONDS = Histogram(
    "http_request_duration_seconds",
    "HTTP request duration in seconds",
    ["endpoint", "method"],
)

CACHE_HITS_TOTAL = Counter(
    "coordinates_cache_hits_total",
    "Total cache hits for coordinates",
)

CACHE_MISSES_TOTAL = Counter(
    "coordinates_cache_misses_total",
    "Total cache misses for coordinates",
)

OPENMETEO_CALLS_TOTAL = Counter(
    "openmeteo_api_calls_total",
    "Total calls made to Open-Meteo Geocoding API",
    ["city"],
)


class RequestTimer:
    """Small helper to measure request duration and emit metrics."""
    def __init__(self, endpoint: str, method: str):
        self.endpoint = endpoint
        self.method = method
        self.start = None
        self.status = "200"

    def __enter__(self):
        self.start = time.time()
        return self

    def set_status(self, status: str):
        self.status = status

    def __exit__(self, exc_type, exc, tb):
        HTTP_REQUESTS_TOTAL.labels(
            endpoint=self.endpoint, method=self.method, status=self.status
        ).inc()
        HTTP_REQUEST_DURATION_SECONDS.labels(
            endpoint=self.endpoint, method=self.method
        ).observe(time.time() - self.start)